Making (single sided) PCB's with Fireball router

[GRB352]

The holes are too small, but I plan to widen the diameter with a drill. I don't have the perfect router bit to do it right the first time.

Technically this will work as all the traces are isolated, but if I don't solder perfectly there will be more chance of shorts. Next I will try a "pocket cut" to remove everything but the traces instead of "engrave cut" like I did here.


Work flow was KiCAD to DXF (Eddie did the pcb layout/design) then modified in Draftsight (joined all those shapes into simpler/single shapes and shortened some traces)  and then CAMBam for gcode generation., then LinuxCNC to make the cut.

  

Its gets a little technical after this, so unless you plan to try it, you can stop reading now.

I took a trick from Liza and had the router cut me a "pocket" the same size as the uncut PCB board. (using the largest 6mm ball end bit). This ensures the board is perfectly flat, and makes it easy to secure to the work surface. 

Next I drilled the holes, because I figured the drilling might mess up the traces if I engraved first.There is no way I could be precise enough to do it by hand. Those bits are super tiny and really want to break, So I used some slower and safer than necessary speed/feeds. "depth increment" of 0.2mm, and a slow "plunge speed" of 100 (100 what I'm not sure, but I lowered it from 300...mm/something) I also added a "peck distance" of .2mm so it would drill a bit and the raise up before drilling a bit. I used tool 3, and just left the tool diameter and hole diameter to defaults even thought to tool diameter is probably 0.3mm instead of 3mm. I didn't need the drilling cut to do anything but "plunge cut" so the diameter didn't matter. Ideally I would use a endmill bit smaller then the hole I needed so it could spiral cut, which is better but requires the tool diameter and hole diameter be correct.... I was using a super-thin "drill bit" not a "endmill bit" so no spiral cuts for me.

https://youtu.be/1ALBW-VCarc

then for then engraving, I had a couple failures, but the settings that worked were "target depth" of -0.2mm with a depth increment of 0.1mm (so two passes) and a "cut feedrate" of 300 (lowered from 800). keep the feedrate limit in LinuxCNC to 10ipm. I used a v-cutter so I selected tool 10, even though I'm not using a 45 degree v. I don't think it makes much difference for an "engraving cut" because it isn't trying to keep track of the diameter of the cut as it goes deeper (v-bits cut wider as they go deeper).

https://youtu.be/r8ptuJWbBV4

Now even though I have two operations using two different tools, I did not attempt a tool change in the same gcode file. There is no way to rehome Z during tool change, or keep track of the Z offsets for each tool with the router we have so I made one gcode file for drilling, and one gcode file for engraving. This allows me to drill ,then change tools, and rehome the Z without losing track of X and Y before staring the second operation.

[Eddie Reid]

That looks really good!

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[GRB352]

Next I will try this. it is just as isolated, but with more room to solder.  (the red squares and yellow circles are just markers, and not used)  The dots (points) are what I use to drill holes.I find it better to use a point to mark where I want a hole instead of using a circle of the diameter I want. Why?  because it is easier to change the value for diameter than it is to redraw all the circles.

[Liza Kholodkova]

Hey Rob,

Why did you not use a drill bit for the side that you needed the holes to be?

You said the holes you made were too small, but why not just use a bit that can drill the right hole size or even pocket out a diameter hole if the bits are too small?

Liza

On Sun, Mar 13, 2016 at 4:22 PM, GRB352 <gregoryro...@gmail.com> wrote:

Next I will try this. it is just as isolated, but with more room to solder.  (the red squares and yellow circles are just markers, and not used)  The dots (points) are what I use to drill holes.I find it better to use a point to mark where I want a hole instead of using a circle of the diameter I want. Why?  because it is easier to change the value for diameter than it is to redraw all the circles.

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Sincerely,

Liza Kholodkova

Founder of Botsy BeDrawn

Aerospace and Mechanical Engineer

[GRB352]

I have drill bits the proper size, but the router only holds bits of certain diameter. The router bits I did have are so thin I didn't want to risk them breaking under the stress of a spiral cut.  Now that I have holes precisely where they need to be, it will be easy to widen the holes by hand with a drill (or more likely I will attempt to borrow Allen Routes hand vice)

eventually I will purchase a set of the proper router bit and do it right the first time.

[Liza Kholodkova]

Oh ok. Makes sense.

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[Brian Bartholomew]

I'll look, I think I have a pin vise, it's lightweight and will give a good feel
for the size of bit you want to hold.

Brian

[Christopher Hoffman]

That looks great! I have a few projects that could benefit from a custom PCB, I'll have to keep this in the back of my mind!

[GRB352]

Pin vice, yes, not a hand vice.  ;-) Thanks man, but Allen said he would bring his on Tuesday (and would go back and fetch it if he forgets).

[GRB352]

The new version came out pretty good on Tuesday, unfortunately it is backwards....The connectors go on the fiberglass side of the board so the pins stick through to the side with the traces so they can be soldered. When you do that it flips everything.   *grumbles*

I will try again ;-)